New phosphorus containing compounds



Patented June 3, 1952 UNITED STATES NEW PHOSPHORUS CONTAINING '(JOMIOUNDS'v ration of Delaware No Drawing. Application October 29, 1947,

Serial No. 782,952

Claims. 1

The present invention relates to new compounds containing phosphorus and to the uses of such compounds particularly as oxidation inhibiting additives for hydrocarbon products.

In the development of lubricating oils the trend has been to use more and more efiicient refining methods in order to reduce the tendency of the oils to form carbon and deposits of solid matter or sludge. While such highly refined oils possess many advantages, their resistance to oxidation particularly under conditions of severe service is generally decreased and they are more prone to form soluble acid oxidation products which are corrosive. They are generally less effective than the untreated oils in protecting the metal surfaces which they contact against rusting and corrosion due to oxygen and moisture. They also often deposit thick films of varnish on hot metal surfaces, such as the pistons of internal combustion engines.

In accordance with the present invention a new class of chemicalcompounds has been discovered, and these compounds have been found to reduce the tendency of refined lubricating oils and other hydrocarbon products to corrode metal surfaces when added in small quantities to such materials. These additives are particularly active in reducing the corrosion of copper-lead and. cadmiumsilver bearings which are employed in internal combustion engines, and they are likewise effective in inhibiting the oxidation of hydrocarbon products generally and especially those of petroleum origin. These compounds also have the property of improving the load carrying capacity of mineral lubricating oils to which they are added.

The new class of compounds forming the subject of the. present invention are products obtained by reacting organo-substituted acids of phosphorus, more specifically the substituted thiophosphorous, thiophosphoric, thiophosphinic, and thiophosphonic acids, or their salts, with the halides, oxyhalides and sulfohalides of phosphorus. A typical reaction is the following:

Reactionsof this type take place readily without the aid of a catalyst. A suitable solvent, such as petroleum ether, is generally employed, and the halide of phosphorusis added gradually while cooling to control the reaction. It is generally more convenient to employ an alkali metal or ammonium salt of the organo-substituted acid. When an organic solventis employed, the metallic or ammqnium chloride producedin thereaction 2 is usually precipitated and may be removed from the product by filtration.

For purposes of nomenclature the new compounds of the present invention may be thought of as phosphorus triand penta-thiophosphites (di-organothiophosphites) or thiophosphates (diorganodithiophosphates), when the products are formed by the reaction of phosphorus trichloride or phosphorus pentachloride with organo-substituted thiophosphitesand dithiophosphates, respectively. Similarly, products derived from phosphorus oxychloride and phosphorus sulfochloride will be named phosphorus oXy tri-(diorganothiophosphites); phosphorus sulfo tri- (di-organothiophosphites) etc. Similar nomen clature will be applied to products derived from thiophosphinic and thiophosphonic acids. The products may also be thought-of as anhydrides of organo-substituted acids of phosphorus. Thus various compounds produced according tothe method described, by selecting various combinations of organo-substituted acids of phosphorus and halides, oxyhalides or sulfohalides of phosphorus, will have compositions illustratedby the following type formulas in which R represents an organic group:

Phosphorus tri-(di-organo- Phosphorus penta-(di-organodithiophospl ate) ditlnophosphate) Phosphorus oxy-tri-(di- Phosphorussulfo tri-(diorganoditliiophosphate) organodi thiophosphate) [(RO)gP-S-]3P [RzP-S']:4P Phosphorus tri-( di-organothic- Phosphorus tri- (di-organothlo1 Y phosphite) I phosphmate) .groups, alkenyl groups, cycloalkyl groups, and

the like, with or Without the substituents-mentioned.

Since the organo-substituted phosphorus and phosphoric acids are usually prepared by reacting alcohols withsulfides of phosphorus it is possible to use as starting materials a large variety of these compounds. For example, alcohols of the type of ethyl alcohol, isopropyl alcohol, tort.- butyl alcohol, lauryl alcohol, stearyl alcohol, wax alcohols, alcohols obtained by oxidation of petroleum hydrocarbons, oleyl alcohol, sulfurized oleyl alcohol, chlorinated and nitrated alcohols, cyclohexyl alcohol, and the like are suitable materials.

The phosphorus halides which are employed to react with the organo-substituted acids and their salts to form the new compounds of the present invention include all of the well known compounds of of this type, such as phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, phosphorus sulfochloride, phosphorus tribromide, phosphorus oxybromide, phosphorus triiodide, and the like, as well as mixed halides of phosphorus, such as PC12F3 and PBrzFa.

Stated broadly, the new compounds of the present invention may be defined by the general in which R represents a hydrocarbon group which may or may not contain added sulfur, chlorine orv nitro groups, .X and Y each represent oxygen or sulfur, rn, n and h" each represent or 1,

and m is 3 or 5, but is always 3 when n" is 1.

When compounds of the above type are to be formed in which n" is 0, or in other words when there is no free oxygen or sulfur atom attached to the phosphorus in the right hand portion of will be obtained when mixtures of the above described typesof compounds are employed in place of simple compounds, e. g., mixtures of alcohols could be employed to prepare mixed substituted acids of phosphorus and such mixed acids could then be reacted with a halide of phosphorus to obtain a mixed product, but such mixed products would be equally useful for the purposes of the present invention.

As stated above, the herein described new compounds may be advantageously added to mineral lubricating oils and other hydrocarbon products for the purpose of preventing corrosion and generally to inhibit oxidation. For this purpose, the amount of the compounds required are generally from about 0.2% to 5% by weight, relative to the base stock in which they are incorporated. For increasing the load carrying capacity of a lubricating oil to an appreciable extent, somewhat larger quantities, generally of the order of 3% to will be required.

The following examples illustrate the preparation of several examples of the new compounds of the present invention and the testing of certain of these compounds for their corrosion inhibiting effects in lubricating oils. It is to be understood, however, that these examples are not to be considered as limiting the scope of the invention in any way.

Example 1.-Preparation of phosphorus tri- (diisopropyl dithiophosphate) To a stirred suspension of 115.5 g. of ammonium diisopropyl dithiophosphate in 1 liter of petroleum ether contained in a 4-necked 3-liter flask equipped with a stirrer, reflux condenser, thermometer, and dropping funnel, was added a solution of 22.8 g. of P013 in 250 cc. of petroleum ether over a period of one hour (maximum temperature 25 (3.). The mixture was then stirred under reflux for three hours (40-45" C.), after which the reaction mixture was permitted to stand overnight. After filtering off the ammonium chloride, the solvent was evaporated at 45 C., with nitrogen blowing. The white crystal- -line product contained 18.7% phosphorus and 27.5% sulfur.

Example 2.-Preparation of phosphorus tri= (di -z -ethylhexyl dithiophosphate) This preparation was carried out in the manner described in Example 1, using as reagents 117.6 g. of potassium di-Z-ethylhexyl dithiophosphate (prepared-from the acid obtained by reacting 2-ethylhexano1 with P285) and 13.7 g. of PC13. The product was a clear yellow liquid containing 11.4% phosphorus and 16.4% sulfur.

Example 3.-Prepara.tion of phosphorus cry-tri- (di-Z-ethylheaiyl dithiophosphate) This preparation was carried out in the manner described in Example 1, using 117.6 g. of potassium di-2-ethylhexyl dithiophosphate (prepared from the acid obtained by reacting 2 -ethylhexanol with P285) and 15.3 g. of POCls. The product was a clear light brown liquid containing 9.6% phosphorus and 15.4 sulfur.

Example 4.Preparation of phosphorus pen-ta- (diz-ethylhexyl dithiophosphate) This preparation was carried out in the manner described in Example 1, using 117.6 g. of potassium di-z-ethylhexyl dithiophosphate (prepared from the acid obtained by reacting 2-ethylhexanol with P255) and 12.5 g. of P015 (suspended in 200 cc. of petroleum ether). The final product was a clear dark red liquid containing 10.3% phosphorus and 16.7% sulfur.

Example 5.-Laborat0ry corrosion tests Lubricating oil blends were prepared containing 0.25% by Weight of each of the products prepared in Examples 1 to 4, using as a base oil an extracted Mid-Continent paraflinic type lubricating oil of SAE 20 grade. These blends and a sam ple of the unblended oil were submitted to a corrosion test designed to measure the eifectiveness of the new compounds in inhibiting'the corrosiveness of a typical mineral lubricating oil toward the surfaces of copper-lead bearings. The test was conducted as follows: 500 cc. of the oil was placed in a glass oxidation tube (13 inches long and 2% inches in diameter) fitted at the bottom with a inch air inlet tube perforated to facilitate air distribution. The oxidation tube was then immersed in a heating bath so that the oil temperature was maintained at 325 F. during the test. Two quarter sections of automotive bearings of copper-lead alloy of known weight having a total area of 25 sq. cm. were attached to opposite sides of a stainless steel rod which was then immersed in the test oil and rotated at 600 R. P. M., thus providing sufficient agitation of the sample during the test. Air was then blown through the oil at the rate of 2 cu. ft. per hour. At the end of each 4-hour period the bearings were removed, washed with naphtha and weighed to determine the amount of loss by corrosion. The bearings were then repolished? (to increase the' severity-- Oitihe: test) reweighedj and then; subjected" to the test: for additional 4-hour. periods: inlikex manner. The results are given in the following tablexas corrosion life, which indicates the number of hours required for the bearings to lose 100 mg. in weight, determined by interpolation of the data obtained in the various periods.

OBearing 01 [051011 Oil Blend Life (Hrs) thionhos hate).-. 23 Base Oil 4 0. Phosphorus oxy tn-(dl-2ethylhexyl dithiophosphate) 19 Base Oil 0.25% Phosphorus penta-(dr-Z-ethylhexyl dithiophosphate) 18 Example 6.-La uson engine test follows:

Gil-Pb Bearing Oil Weight Loss (mg/bearing) Base Oil 220 Base Oil+0.75%- Phosphorus tn-(dusopropyl dithiophosphate) 95 Theproducts oi the present invention may be employed-not-onl'yin ordinary hydrocarbon lubricating oils but also inthe-heavy duty type of-lubricating.oilswhich have been compounded with such. detergent type additives as metal soaps, metal petroleum. sulfonates, metal phenat'es, metal alcoholates, metal alkyl phenol sulfides, metal organophosphates, thiophosphates, phosphites and thiophosphites,.metal salicylates, met'ali xanthates. and thioxanthates, metal thiocarbamates, amines and amine derivatives, reaction products of metal phenates and sulfur, reaction products of metal phenates and phosphorus sulfides, metal phenol sulfonates, and the like. Thus, the additives of the present invention may be used in lubricating oils containing such other addition agents as barium tert.-octylphenol sulfide, calcium tert.-amylphenol sulfide, nickel oleate, barium octadecylate, calcium phenyl stearate, zinc diisopropyl salicylate, aluminum naphthenate, calcium cetyl phosphate, barium di-tert.-amylphenol sulfide, calcium petroleum sulfonate, zinc methyl cyclohexyl thiophosphate, calmium dichloro-stearate, etc. Other types of additives, such as phenols and phenol sulfides may be employed.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraflinic, naphthenic, asphaltic or mixed base crudes. or, if desired, various blended oils may beemployedas:welkasresiduals.particularly those from l which. asphal-tic: constituents; have been carefully-removed: The oils may, be'refined by conventional methods.- using acid, alkaliandl or clay or otheragentssuch asaluminum chloride; or they may be extracted oils produced, for ex-.- ample, by solvent. extraction with-solvents of the type of phenol, sulfur dioxide, furfural, dichloe rodiethyl ether; nitrobenzene, crotonaldehyde, etc. Hydrogenated oils or white oils may be emp'loyed' as-well assynthetic oilsprepared, for ex! ample, by-the polymerization of olefins or by'the reaction of oxides of carbon with-hydrogen, or bythe' hydrogenation of coal or its products. In certain: instances crackingcoal tarfractions and coal tar or shal'e oil distillates: may also housed; Also for special applications. animal, vegetable or fish oils or their hydrogenated or voltolized products may be employed in admixture with mineral oils.

For the best results the base stock chosen should normally be that oil which without the new additive present gives the optimum performance in the service contemplated. However, since one advantageof the additives is; that their use also makes feasible the employment of less satisfactory mineral oils or other oils, no strict rule can be laid down for the choice of" the ,base stock. Certain essentials must of course be observed. The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The oil must'be a satisfactory solvent for the additive, although in some cases auxiliary solvent agents maybe used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon. the particular use for which they are desired, but they usually range from about 40 to seconds Saybolt v i s..- cosity at-210 'F. For the lubricating of certain low and medium speed diesel engines the general practice has often been to use a lubricating oil base stock prepared from-naphthenic or aromatic orudes and having a- Saybolt viscosity at 210 F. of 45 to- 90. seconds anda viscosity indexoio to 50.; However, in certain. types of; diesel engine and other gasoline engine service, oils of higher viscosity'index are often preferred, for example up to '75 to 100,, oreven higher, viscosity-index.

In addition to the; materials to beadded according to the present invention, other agents may also be used such as dyes, pour depressors, heat thickened fatty oils, sulfurized fatty oils, organo-metallic' compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized fats, voltolized mineral oils, and/or voltolized waxes and colloidal solids such as graphite or zinc oxide. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds, and the like may also be employed.

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having eight or more carbon atoms and preferably 12 to 20 carbon atoms. The alcohols may be saturated straight and branched chain aliphatic alcohols such as octyl alcohol (CsHnOH), lauryl alcohol, (C12H25OH), cetyl alcohol (C1sH33OH), stearyl alcohol, sometimes referred to as octadecyl alcohol, (CmHa'zOH), heptadecyl alcohol (CnHasOH), and the like, the corresponding olefinic alcohols such as oleyl alcohol, cyclic alcohols such as naphthenic alco hols; and aryl substituted alkyl alcohols, for instance, phenyl'oct'yl alcohol, or octadecyl benzyl alcohol or mixtures o1 these various alcohols, which may be pure or substantially pure synthetic alcohols- One may also use mixed naturally occurring alcohols such as those found in wool fat (which is known to contain a substantial percentage of alcohols having about 16 to 18 carbon atoms) and in sperm oil (which contains a high percentage of cetyl alcohol) and although it is preferable to isolate the alcohols from those materials, for some purposes, the wool fat, sperm oil or other natural products rich in alcohols may be used per se. Products prepared synthetically by chemical processes may also be used, such as alcohols prepared by the oxydation of petroleum hydrocarbons, e. $3., paraflin wax, petrolatum, etc.

In addition to being employed in crankcase lubricants the additives of the present invention may also be used in extreme pressure lubricants, engine flushing oils, industrial oils, general machinery oils, process oils, rust preventive compositions and greases.

The additives of the present invention may be employed as antioxidant or stabilizing agents not only in mineral lubricating oils, but also in hydrocarbon products generally, where improved resistance to oxidation is desired. Thus, the products may be added to motor oils, diesel fuels, kerosene, waxes, hydrocarbon polymers, natural and synthetic rubbers, etc.

The present invention is not to be considered as limited by any of the examples described herein, which are given by Way of illustration only, but-is to be limited solely by the terms-of the appended claims.

I claim:

1. An essentially hydrocarbon oil product having incorporated therein at least a corrosion inhibiting amount of a compound of the formula in which R is an alkyl group having in the range of 3 to 8 carbon atoms, X is selected from the group consisting of oxygen and sulfur, n is a number from to 1, and m is an odd number from 3'to 5, but is 3 when n is 1.

2. A composition according to claim 1 in which the hydrocarbon product is a mineral lubricating oil.

3. A composition according to claim 1 in which R of the formula is an isopropyl group.

8 4.1 A composition according to claim 1 in which R of the formula is a Z-ethylhexyl group.

5. As a new composition of matter a compound of the formula where R i an alkyl group.

6. As a new composition of matter a compound of the formula where R is an alkyl group.

'7. As a new composition of mattera compound of the formula:

JOHN P. MCDE RMOTT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,411 Romieux et a1 June 15, 1937 2,038,400 Whitworth Apr. 21, 1936 2,242,260 Prutton May 20, 1941 2,336,302 Schrader Dec. 7, 1943 2,343,831 Osborne Mar. 7, 1944 2,514,150 Bell July 4, 1950 2,526,497 Mikeska Oct. 17, 1950 

1. AN ESSENTIALLY HYDROCARBON OIL PRODUCT HAVING INCORPORATED THEREIN AT LEAST A CORROSION INHIBITING AMOUNT OF A COMPOUND OF THE FORMULA 